Rattlecan. Airbrush. Brush-on. These are the primers that we as miniature painters are so often slaves to in our hobby. We need these to do our jobs, and not using them places our work at risk and can limit our ability to create what we want to create.
Some have said priming is optional, and this is mostly true. As we know, an acrylic paint is tough, waterproof, and looks great own its own. But without a primer there’s a much greater risk that your paint will come off when you’re engaging in glazing, dry-brushing, and just painting over it with another. It can also become less durable and easier to remove on accident.
Playing with primers has fascinated me since I basically learned they existed last year. I, like many, started painting by putting a bit of paint on a model straight-up. And not just any paint: Speed paint. So the paint just beaded and washed away without any effect, much to my chagrin. I bought some airbrush primer to brush on after that and then moved up to rattlecan once I felt more confident. I later bought some gesso as an experiment and then when I got an airbrush I played around with three types of primer there. So I feel like this would be a great block to write about these things since they fascinate me so much.
But without a primer there’s a much greater risk that your paint will come off when you’re engaging in glazing, dry-brushing, and just painting over it with another.
Thoughts about what’s best and what isn’t are purely subjective and my opinions alone. Your views may vary. I am not an expert, but I play with these things in a high-humidity environment so I have an angle of perspective many others don’t.
I’m going to divide these by method of application, since some primers can be used in multiple ways.
Final bit of advice: Always wash your minis first with soap and water! The manufacturing process often involves oils to help remove them from their molds. These force chemicals like the ones also in primers to not stick. Proper cleaning removes them.
Rattlecan
Rattlecan primers come in two forms: Dedicated miniature spray paint and hardware spray paint. Each has their own advantages and disadvantages. Both share the problem that they are highly sensitive to the weather since their sensitive aerosol compounds have to maintain pressure in the can then project the paint out the nozzle all while mixing into the environment and keeping the paint intact to reach its target. But the end result is typically the best and can go on in seconds.
If you use these above 75% humidity (or if it’s raining/snowing in any capacity) then water mixes into the aerosol and then the paint itself. This can cause the paint to apply in heavy globs or even never cure properly, leaving it sticky or wet for days or even weeks. Sometimes they never dry at all.
I have never experienced this, but I understand that using these below 40% can cause the paint to dry in mid-air, meaning adhesion never happens properly, weakening the final coat and preventing proper curing, too. I also understand they don’t work in cold temperatures at all.
Dedicated miniature spray paint. This stuff is the most forgiving, most friendly primer you can use and can be paintable in 30 minutes. It seems to experience the tackiness-stickiness issue the least, but it lacks some of the etching chemicals hardware paint has, resulting in lower durability. They come in a variety of colors and are typically perfectly formatted for painting onto miniatures while providing a minimum of needless texture.
On the opposite end, white spraycan miniature paint is usually extremely chalky and textured to the point of ruining the model. (Note: I’ve heard Citadel’s is OK apparently? Never used it, so I don’t know. But Army Painter’s white is bad enough it made me swear off the stuff. No interest in ruining any more minis since I’ve effectively moved on.)
The main issue with using this paint is it is often quite expensive, running $15-25 for just one can. It also is only sold at hobby stores.
Hardware spray primer. Far less forgiving but with a host of advantages of its own, this is my go-to primer in most instances, especially for big projects.
Typically running $6-8, rattlecan primer by brands like Rustoleum and Krylon (in the U.S.) provides a variety of colors and finishes for a fraction of the price with higher availability as it can be found anywhere that sells spray paint. It also does not produce the same kind of chalkiness with white, though it will still spatter quite a bit (which is just kind of the nature of white paint). Further, the finished result is very, very durable and (if you make sure to get the flat or matte ones) provides an extremely good painting surface.
But if you are above the 75% humidity range, these will be tacky for an extremely long time, sometimes never properly drying. They are also easy to over-apply, which will produce the same result. (I have not experienced what happens at lower humidities. I live in Florida.) Painting over tacky primer can lead to your acrylics cracking (which may be kinda cool sometimes?). Even without the humidity it can take a few days for this to fully cure, which can suck if you’re on a tight schedule or anxious to get started.
Additionally, these have solvents in them to help them etch into the plastic. This improves durability. But this also makes removing the primer if you need to strip extremely challenging, and can corrode details on a miniature if done too many times. Many painters refuse to use these for this reason, as it can reduce the life of a miniature. But if you’re not the kind of person who strips models or if you use plastics that aren’t susceptible to these solvents (like PVC or 3D resin), then these have no real disadvantages in this area. (Note: Reaper Bones plastic does not take these well at all, and they often will never cure. Caused me many headaches. I have a large model I waited five days to cure and it never did completely. I ended up patching up the remaining sticky spots with airbrush polyurethane primer.)
That said, if painting on a proper surface in proper weather with a proper number of coats and with enough time to let it dry, the end result is pretty fantastic for a good price.
Brush-On
Brush-on primers come in a few common forms. Many paint brands offer a dedicated brush-on primer, and these are great options for bad weather. You can also use gesso and airbrush primer. You can apply any of these like a base coat and, if the model is clean, go on great with little fuss. Since it is applied like a paint, make sure you don’t over-do it. Apply it in thin coats and don’t let it clog details. It will shrink as it dries but isn’t miraculous. However, since you’re painting it it is the slowest method by far. I only use this when I absolutely have to, don’t feel like dragging out the rattlecans or airbrush, or if I’m just down for a chill base-coating session.
Dedicated Brush-On. These come in standard miniature paint dropper bottles and are applied like a base-coat to bare plastic or metal. I don’t have any experience with the dedicated brush-on primers you get in dropper bottles, but based on this video they seem to be the highest-performing of the brush-on options. Army Painter only offers gray, but Reaper offers black, white and gray colors. Vallejo offers many more. I’d imagine these would go through an airbrush fine if thinned, though this will probably risk the durability.
The biggest issue with these, much like the dedicated miniature spray primers, is they don’t give you much for the price. Gesso and airbrush primers are available and have many, many more milliliters for the same cost with almost the same performance.
Gesso. My personal go-to for brush-on primer, this is artist primer and comes typically in dropper bottles or pots and is usually meant for canvases or sculpting. I prefer Golden Artist Colors gesso, since it seems to be the highest quality with the least amount of odor. Liquitex is extremely smelly. You can buy huge tubs of this stuff for pennies on the dollar with some brands, but I doubt the quality is really there. Then again, it’s primer so who cares as long as it does its job?
I’ve heard this stuff described as a liquid plaster or chalk while still counting as acrylics, and that does seem to be about right. It has a serious amount of tooth, giving paint a perfect working surface that is almost excessively matte and durable. It can give a hint of texture, but not enough that it is noticeable once painted. Black gesso has a beautiful matte coat that is a dream to paint on. White doesn’t, but it still provides the same tooth. Gesso does stain though, so make sure you clean it properly.
This is the only primer I’ve seen that offers a clear version. I don’t see the point for our hobby, but what the hell, right?
Airbrush Primer. 95% of people use this for their brush-on primers when they need them. I would absolutely agree that these are great options because they easily translate into being, well, regular airbrush primer once you move to an airbrush.
You get quite a bit for a good price, and even using it frequently you will probably never use it up in this purpose.
My only real criticism is it needs multiple coats to provide good coverage. You can use it with one coat and then just base coat it with something else though, as even a thin coat will provide enough tooth for painting. Probably the most generally useful all-around brush-on option.
Airbrush
The reigning king of miniature priming methods. This stuff is applied with, well, an airbrush, and provides both speed and weather immunity, giving you the best of both worlds. I am going to cover the three types of primer I know of through this method, though you might know of more. You can also use gunpla-style enamel primers, but I won’t cover those here except in discussing polyurethane because I simply have (and may never have) any experience with this stuff.
Polyurethane: Considered by many to be the pinnacle of the priming experience, these are the most commonly used of airbrush primers. Polyurethane provides an even, level coat that contracts as it dries, providing little issues covering detail in a highly durable finish. If you put a few drops of these on a dry palette, you’ll find they dry into a rubbery-like substance. So basically you’re covering your mini in something like toothy rubber.
My experience painting on this is simply divine. It feels great to paint on and just looks good on its own. Dries well on everything, too. There’s very little to hate here.
Stynylrez (from Badger Airbrush), Vallejo and Pro Acryl (from Monument Hobbies) offer these primers. There’s probably more brands out there since it’s fairly ubiquitous.
As a side note, Jon Ninas (Ninjon) has been talking about polyurethane and its tendency to expire and, well, turn into a chunky mess after about a year in the bottle. If you do some Googling on “polyurethane expires,” you’ll find several blogs that talk about how yes, polyurethane will expire after a year. Basically it congeals in the container. He’s moved on to Mr. Hobby Mr. Surfacer. This stuff’s really toxic though and since I just heard about it this week I am not super interested in covering it yet. (Personal note: I also have a bias against products that only one company offers. I very much prefer being able to jump brands if reason presents. This alone is keeping me away from this stuff for now.)
Army Painter Airbrush Primer. A fairly new entry in this field, I have a bottle of this stuff and I don’t know quite what to do with it. It’s more of a regular acrylic, and it goes very well through an airbrush and provides a simply divine surface to paint on when it works. But it has one huuuuuge flaw: durability seems to be a major problem, or at least is just really inconsistent.
I always clean my miniatures before I prime them to ensure my primer has a clean surface to work on. And I’ve used this stuff and had excellent results one time, then done it again on another model and it basically is like dust, rubbing off from the simplest of contact.
Bottles are a bit pricey too compared to the polyurethane stuff, which run about 33% cheaper per ml. Negligible at low dollar amounts but there.
Since this doesn’t have a shelf life, I imagine it’ll come back into my rotation at some point if I can get it to stop abrading.
Edit 4/25: (Two weeks later) I am no longer getting the durability issue anymore. I can only guess what happened, but I suspect too much water got into the pot with the primer. It may be highly sensitive to thinning. This has MASSIVELY improved my perspective on it, and would make it my most recommended primer if I could guarantee it wouldn’t do that again.
Gesso. OK, OK, this one’s kind of out of left field and it’s kind of my own invention. But I’ve found this stuff actually works pretty well. Golden Artist Colors (GAC) gesso says it can be thinned down 20% with water, and I’ve found that to be true enough that it goes through an airbrush at that point.
However I do something a little bit different: I thin it down with High Flow Medium. This maintains the integrity of the acrylic gesso while improving the flow and durability. Basically you make it about 50-50 or as thin as skim milk (as you should with anything going through an airbrush) and use that. It’ll dry as fast as a normal airbrushing and provide a durable, paintable surface that’s also less toxic to spray.
To be honest, long-term I expect this to be my main airbrush primer. It seems to have none of the disadvantages of any of the others and all of the advantages of painter’s gesso. The only down side is I have to mix it myself. Testing will continue, and if I’m wrong I’ll cross this off the list.